Interest in body_peek filter ( access to body without consume it )

[AtsukiTak]

I'm interesting in body_peek filter because it will make it easy to implement JSON RPC filters.

What I'd like to implement

let add_rpc_filter = json_rpc::method("add")  // matches "add" rpc method
    .and(json_rpc::params::<(u8, u8)>())  // matches rpc parameter
    .and(authenticate())    // some user defined filter
    .and_then(|a, b| future::ok(a + b))
    .and_then(json_rpc::reply());

let another_rpc_filter = ...;

let rpc_filter = filters::path::("rpc")
    .and(add_rpc_filter.or(another_rpc_filter));

The hard part

json_rpc::method and json_rpc::params filters need to access Body. But it will panic when Body is accessed more than once.

Ideas to solve it

1. To access Body using filters::body::body_peek or filters::body::json_peek filter.
   Such filter allow us to access Body more than once.

2. Add extension to store extracted Body data.
   Perhaps, this is better than above but I'm not sure how to do it without direct use of hyper.
   According to Consider removal of warp::ext::set #222 , I should use Service directory and if my understand is correct, I should provide the mechanism almost same with warp's server module by myself. Is it right?

3. Do you have any ideas?
   I probably don't understand warp enough. So if you let me know another idea, I'm very very happy!

Thank you!

[AtsukiTak]

I'm working on warp::ext::with_mut(impl Fn(&mut Extensions)) .
#222 (comment)

[AtsukiTak]

I have created PR #457 but it might have some issues...
So for now, I personally use custom Service which wraps FilteredService. It seems to work well :)

[haarts]

@AtsukiTak could you give me a nudge in the right direction? Perhaps a code snippet? I'm struggling.

[AtsukiTak]

@haarts Hi. I chose solution 2 listed above.

2. Add extension to store extracted Body data

To do that, what I did are

1. convert Filter into Service using warp::serivce.
2. prepare a space for extracted body. sample code

After that, when I want to touch request body,

1. get from that space if it is filled.
2. extract from request.

sample code

I hope this would help you :)